Microscale (including nanoscale) moving structures are currently the subject of intense interest due, in part, to their potential applications in micromachines. The creation of miniature engines that can convert chemical energy to motion is one of the great remaining challenges of nanotechnology.
There is great difficulty of delivering energy from a macroscopic source to an individual microscale structure. As used here, the term microscale includes nanoscale structures (or nanostructures). Hence, it would be advantageous if external energy sources were not necessary, for example through the use of autonomous structures that do not require an external energy source.
Enzymatic catalysis of spontaneous reactions is known in biology, such as the hydrolysis of ATP and GTP. Microscale motors driven by catalysis have not been demonstrated in non-enzymatic systems. Nanotube-based actuators are also known, but movement is powered by an external, macroscopic energy source.
Whitesides and coworkers have used hydrogen peroxide decomposition to propel larger-scale structures on a water surface, using the recoil force of oxygen (O2) bubbles, for example as described in R. F. Ismagilov, A. Schwatrz, N. Bowden, G. M. Whitesides, “Autonomous Movement and Self-Assembly,” Angew. Chem. Int. Ed. 2002, 41, 652-654. However, the generation of macroscopic bubbles could interfere with the operation of micromachinery, especially nanomachinery.
U.S. Patent App. Pub. No. 2003/0215844 to Chapsky et al. describes single molecule detection of bioagents, using DNA hybridization techniques. U.S. Pat. App. Pub. No. 2003/0142901 to Lahann et al. describes surfaces having reversibly switchable surface properties. U.S. Pat. App. Pub. No. 2003/0159943A1 to Smalley et al. describes methods of forming arrays of single wall nanotubes. Int. Pat. App. Pub. No. WO03/101955A2 to Anquetil et al. describes molecular actuators. Int. Pat. App. Pub. No. WO03/025145A2 to Evans describes a basic genetic operating system for an autonomous prototrophic nanomachine. Int. Pat. App. Pub. No. WO00/22101 to Montemagno describes integration of a molecular motor in a nanomechanical system. U.S. Pat. No. 6,645,455 to Margrave et al. describes methods of synthesizing self-assembled arrays of carbon nanotubes. U.S. Pat. No. 5,426,942 to Suzuki et al. describes methods of driving microbodies along a substrate that is hydrophobic at low temperatures and hydrophilic at high temperatures.
However, the prior art fails to disclose autonomous microstructures having catalyst regions such as described herein. Patents and patent applications referenced in this specification are incorporated herein by reference.